nimgrep: introduce the --rex option

tools/nimgrep.nim

@@ -11,7 +11,7 @@ import
   os, strutils, parseopt, pegs, re, terminal
 
 const
-  Version = "1.3"
+  Version = "1.4"
   Usage = "nimgrep - Nim Grep Utility Version " & Version & """
 
   (c) 2012 Andreas Rumpf
@@ -21,8 +21,9 @@ Options:
   --find, -f          find the pattern (default)
   --replace, -r       replace the pattern
   --peg               pattern is a peg
-  --re                pattern is a regular expression (default); extended
-                      syntax for the regular expression is always turned on
+  --re                pattern is a regular expression (default)
+  --rex, -x           use the "extended" syntax for the regular expression
+                      so that whitespace is not significant
   --recursive         process directories recursively
   --confirm           confirm each occurrence/replacement; there is a chance
                       to abort any time without touching the file
@@ -44,7 +45,8 @@ Options:
 type
   TOption = enum
     optFind, optReplace, optPeg, optRegex, optRecursive, optConfirm, optStdin,
-    optWord, optIgnoreCase, optIgnoreStyle, optVerbose, optFilenames
+    optWord, optIgnoreCase, optIgnoreStyle, optVerbose, optFilenames,
+    optRex
   TOptions = set[TOption]
   TConfirmEnum = enum
     ceAbort, ceYes, ceAll, ceNo, ceNone
@@ -290,6 +292,10 @@ for kind, key, val in getopt():
     of "re":
       incl(options, optRegex)
       excl(options, optPeg)
+    of "rex", "x":
+      incl(options, optRex)
+      incl(options, optRegex)
+      excl(options, optPeg)
     of "recursive": incl(options, optRecursive)
     of "confirm": incl(options, optConfirm)
     of "stdin": incl(options, optStdin)
@@ -345,7 +351,8 @@ else:
       pattern = r"\b(:?" & pattern & r")\b"
     if {optIgnoreCase, optIgnoreStyle} * options != {}:
       reflags.incl reIgnoreCase
-    let rep = re(pattern, reflags)
+    let rep = if optRex in options: rex(pattern, reflags)
+              else: re(pattern, reflags)
     for f in items(filenames):
       walker(rep, f, counter)
   stdout.write($counter & " matches\n")